Air Pollution High in California Cities

April 29, 2009 -- Areas in California remain some of the most polluted in the U.S., with air quality that is likely damaging the health of millions of people, according to a report by the American Lung Association.

The report finds that Los Angeles, Bakersfield, Calif., and Visalla-Porterville, Calif., rank among the five U.S. cities most polluted with particulate and ozone pollution.

Almost 186.1 million Americans live in places where the air quality is probably bad enough to damage their health, at least part of the year, the report concludes.

The Pittsburgh-New Castle area in Pennsylvania ranked the worst in the nation for short-term particle pollution and second for the most year-round particle pollution. Particulates come from a variety of sources, including diesel and gasoline engines, power plants, construction and demolition projects, soil, and dust.

Breathing particulates can cause lung inflammation that can exacerbate diseases like asthma and chronic bronchitis, but also can contribute to cardiovascular disease including heart attack and stroke.

After Pittsburgh-New Castle, the cities with the worst particle pollution over a 24-hour period include:

Fresno-Madera, Calif.-Bakersfield, Calif.

Los Angeles-Long Beach-Riverside, Calif.

Birmingham-Hoover-Cullman, Ala.

Salt Lake City-Ogden-Clearfield, Utah

Sacramento-Arden-Arcade-Yuba City, Calif.-Nev.

Levels of ozone have dropped nationwide over the last decade, and the Environmental Protection Agency slapped tighter restrictions on the pollutant in 2007. Still, dozens of U.S. cities regularly have unsafe ozone levels, the American Lung Association says.

Ozone is created when exhaust from car engines and other fuel-burning sources reacts with sunlight. Ozone can cause irritation of the airways and lung inflammation; it can quickly worsen diseases like asthma and emphysema.

Last year the National Academy of Sciences concluded that short-term ozone exposure was "likely to contribute" to premature deaths.

After Los Angeles-Long Beach-Riverside, the cities with the worst ozone pollution in 2008 were:

Bakersfield, Calif.

Visalla-Porterville, Calif.

Fresno-Madera, Calif.

Houston-Baytown-Huntsville, Texas

Sacramento-Arden-Arcade-Yuba City, Calif.-Nevada

Dallas-Fort Worth, Texas

"More than 175 million Americans live in areas with unhealthy smog levels; that's 80 million more than we identified in last year's report," says Charles D. Connor, American Lung Association president and CEO.

The increase is partly due to changes in the way the Environmental Protection Agency categorizes ozone levels; lower ozone levels than before are now considered unhealthy, so more people fall into the unhealthy category.